The Hijacked Connection
When you connect an iPhone or iPad to your Mac via a Lightning or USB-C cable, macOS automatically launches the Photos app and begins preparing to import all the new photos and videos from the device’s camera roll. If your iPhone contains thousands of photos, this import preparation can take considerable time, during which the Photos app consumes CPU and memory resources. For users who only connected the iPhone to charge it, to transfer a file via Finder, or to use it as a development testing device in Xcode, the automatic Photos launch is an unwelcome interruption that must be manually dismissed every single time.
Preventing Photos from Auto-Launching
To stop macOS from automatically opening the Photos app every time you connect an iPhone, iPad, or camera, you must change the import setting within the Photos app itself.
First, connect your iPhone or iPad to your Mac. Allow the Photos app to open (or open it manually if it does not launch). In the Photos app, your connected device will appear in the left-hand sidebar under “Devices.” Click on your device name. At the top-left corner of the import view, look for a checkbox labelled Open Photos for this device (on older macOS versions, this is a drop-down menu at the top-left that says “Open Photos”). Uncheck this box, or change the drop-down to No application. This setting is saved per-device, so you must repeat this step for each iPhone, iPad, or camera you regularly connect. From this point forward, connecting that device will not trigger Photos to launch. If you later want to import photos, you can always open Photos manually and navigate to the device in the sidebar. Alternatively, you can set the drop-down to open Image Capture instead, which provides a lighter-weight import interface without the full Photos library overhead.